diff --git a/lib/sinon/spy.js b/lib/sinon/spy.js
index 5d783565f..142395c21 100644
--- a/lib/sinon/spy.js
+++ b/lib/sinon/spy.js
@@ -22,6 +22,14 @@ var filter = Array.prototype.filter;
 
 var uuid = 0;
 
+function matches(fake, args, strict) {
+    var margs = fake.matchingArguments;
+    if (margs.length <= args.length && deepEqual(slice(args, 0, margs.length), margs)) {
+        return !strict || margs.length === args.length;
+    }
+    return false;
+}
+
 // Public API
 var spyApi = {
     formatters: require("./spy-formatters"),
@@ -44,7 +52,7 @@ var spyApi = {
         };
 
         forEach(original.args, function(arg, i) {
-            if (!fake.matches(arg)) {
+            if (!matches(fake, arg)) {
                 return;
             }
 
@@ -64,20 +72,10 @@ var spyApi = {
     // Override proxy default implementation
     matchingFakes: function(args, strict) {
         return filter.call(this.fakes, function(fake) {
-            return fake.matches(args, strict);
+            return matches(fake, args, strict);
         });
     },
 
-    matches: function(args, strict) {
-        var margs = this.matchingArguments;
-
-        if (margs.length <= args.length && deepEqual(slice(args, 0, margs.length), margs)) {
-            return !strict || margs.length === args.length;
-        }
-
-        return undefined;
-    },
-
     printf: function(format) {
         var spyInstance = this;
         var args = slice(arguments, 1);